When running reftests on Mulet, we do not want that forced update
checking gets triggered. We can block this by setting the following
prefs:
- app.update.enabled to false
- app.update.url.override and app.update.url to empty string
We also disable tiles-related pinging and downloading by setting empy
values for:
- browser.newtabpage.directory.source
- browser.newtabpage.directory.ping
Gaia also does force check app updates at some point, so we introduce a
new pref, webapps.update.enabled, that we can use to make sure webapps
update won't be triggered.